Mobile communications have become common place throughout society. Not only is voice communications prevalent, but also the need for mobile data communications such as email, and Internet browsing has increased. The efficiency of RF systems in mobile communications, such as antenna efficiency of a mobile device as it undergoes changes in its environment, can affect among other things the quality of communications experienced by mobile subscribers. Efficient RF power transfer, or good impedance matching, can affect the performance of RF subsystems, such as at the input port of an antenna, between filters, at the output stages of power amplifiers, and even inter-stage matching between amplifier stages.
Impedance matching networks can be used by various devices and systems, for example, a transmitter, a receiver, a transceiver, a wireless communication station, or a wireless communication device. Examples of RF systems that can utilize impedance matching networks include without limitation, a wireless Access Point (AP), a modem, a wireless modem, a computer (e.g., desktop computer, a mobile computer, a laptop computer, a notebook computer, a tablet computer, a server computer, a handheld computer, a handheld device, a Personal Digital Assistant (PDA) device, a network, a wireless network, a Local Area Network (LAN), a Wireless LAN (WLAN), a Metropolitan Area Network (MAN), a Wireless MAN (WMAN), a Wide Area Network (WAN), a Wireless WAN (WWAN), devices and/or networks operating in accordance with existing IEEE 802.11x, 802.16x standards and/or future versions and/or derivatives and/or Long Term Evolution (LTE) of the above standards, a Personal Area Network (PAN), a Wireless PAN (WPAN), units and/or devices which are part of the above WLAN and/or PAN and/or WPAN networks, one way and/or two-way radio communication systems, cellular radio-telephone communication systems, a cellular telephone, a wireless telephone, a Personal Communication Systems (PCS) device, a PDA device which incorporates a wireless communication device, a Multiple Input Multiple Output (MIMO) transceiver or device, a Single Input Multiple Output (SIMO) transceiver or device, a Multiple Input Single Output (MISO) transceiver or device, a Multi Receiver Chain (MRC) transceiver or device, a transceiver or device having “smart antenna” technology or multiple antenna technology, or the like.
The above RF systems can utilize any number of RF signaling techniques such as, for example, Frequency-Division Multiplexing (FDM), Orthogonal FDM (OFDM), Time-Division Multiplexing (TDM), Time-Division Multiple Access (TDMA), Extended TDMA (E-TDMA), General Packet Radio Service (GPRS), Extended GPRS, Code-Division Multiple Access (CDMA), Wideband CDMA (WCDMA), CDMA 2000, Multi-Carrier Modulation (MDM), Discrete Multi-Tone (DMT), Bluetooth®, ZigBee™, or the like.
The above RF systems can utilize impedance matching networks whose load impedance can vary with time, temperature, power levels, component values, and many other communication parameters.